It is desired to use a material having a high reflectivity as an electrode in order to improve light extraction efficiency of a semiconductor light emitting device such as an LED (Light Emitting Diode). Silver or silver alloy exhibits high reflection characteristics also to short-wavelength emission light of 400 nm or less and is excellent in electrical characteristics, such as ohmic characteristics and contact resistance. On the other hand, in silver or silver alloy, migration and chemical reaction are prone to occur and furthermore, adhesiveness is low. In a semiconductor light emitting device using such silver or silver alloy as an electrode, there is room for improvement to achieve a still higher reflectivity, higher electrical characteristics, higher stability, and higher adhesiveness.